In the prior art, a telecommunications system implementing the above-described method includes a main communications network such as a switched telephone network capable of setting up a link between a terminal made available to the user with at least one first communications means implemented by a first customer, called an upstream customer, identified as being the first intended recipient of a communications call that will have been initiated by the user, for example by keying in a predefined code on an alphanumeric keypad with which his terminal is provided. This first communications means could be for example a home-page type voice server capable of receiving a verbal request and of orienting this request, and hence the communication call in progress, to a second communications means implemented by another customer, called a downstream customer, who will have been identified by the upstream customer as a supplier of a service capable of responding to the requests formulated by the user. The term “customer” must be understood here and further below in the description as designating an entity who calls upon the resources of another entity in order to perform a task, a customer possibly taking the form of an autonomous server, a group of servers or various elements distributed separately within various communications means included in the system.
In the prior art system, when the upstream customer reorients the communication calls to the downstream customer, this upstream customer can preliminary store the service information at a particular location of a memory space included in an intermediate unit constituted by an auxiliary server and, through a signaling link planned for this purpose, send an address enabling the identification of said particular location. As it happens, this address is formed by a combination of an IP (Internet protocol) address well known to those skilled in the art, assigned to the auxiliary server, and an address of a memory port, internal to said auxiliary server, where the service information will have been effectively stored.
In the prior art, no particular precaution is planned as regards the assigning of port addresses by the auxiliary server, so that a port address could be reassigned, during a session, to a third-party customer external to the session in progress, said third-party customer then being capable, through an operation for writing new data at the port address considered, of prompting an overwriting of the service information initially stored at this port address.
Thus, the fact that any third-party customer capable of reaching the auxiliary server can request write-access thereto gives rise to considerable risks for the integrity of the information stored in said auxiliary server.
Furthermore, if a use session is defined as a sequence of successive activations of different communications means, such as for example the terminal of the user and servers implemented by the upstream and downstream customers referred to here above, the inventors have noted that, in the prior art, the pieces of service information stored by one of these communications means are linked to it and are destined to disappear very quickly after this communications means has stopped intervening in the session in progress. Now, according to the definition of the use session which is the one that the inventors propose to implement, an interruption of a communications call of one of the communications means drawn into the communications line during a use session should not prompt a break in continuity of said use session. In particular, it should be possible for a participant, whether a user or a customer, to interrupt his communications call without the use session itself being in any way thereby interrupted, and servers such as the servers implemented by the upstream and downstream customers referred to here above should be capable in such a situation of taking over and proceeding off-line to a processing of data given by the participant before calling him to give him the results of the processing operation. In known telecommunications systems, this kind of continuity of the use session in progress cannot be accompanied by a continuity of existence of the service information so that at present it is not possible to envisage the setting up of use sessions where one or more acting parties could disconnect temporarily or permanently without thereby giving rise to an interruption of the data processing system.
Thus, in general, in known telecommunications systems, there is no guarantee of the perenniality of the service information stored in the auxiliary server. Furthermore, if a participant in the course of a session orders a dynamic storage of service information additional to service information previously stored by this same participant, it is not possible to set up any link between the additional service information and the information previously stored, whereas such a link would in principle be useful for intended recipients of this information who could, for example, have to perform simultaneous processing of all the pieces of service information, and this processing would then be facilitated by a grouping together of these pieces of information.